Contact lenses are medical devices that are placed in contact with the ocular surface and are used for vision correction, aesthetic purposes, and to treat ocular pathologies. Substances and materials can be deposited onto a contact lens's surface to improve the biocompatibility of the lens and therefore improve the interaction of the lens with the ocular region.
The current generation of contact lenses commonly includes a silicone containing core material. These lenses have many advantages over their rigid plastic predecessors. For example, silicone-containing lenses are biocompatible for the eye and have improved oxygen and fluid permeability for normal ocular surface health. However, despite these advantages, a major challenge for silicone-containing lenses is the hydrophobicity of silicone containing materials, which can lead to abrasion of ocular tissue and infection. As such, embodiments described herein provide for a contact lens having improved hydrophilicity and biocompatibility as well as practical and cost-effective methods for making these lenses.
Rigid gas permeable (RGP) lenses are another alternative to soft contact lenses. RGP lenses are designed for longer term wear than soft lenses and can provide crisper vision than current soft lenses. RGP lenses can also automatically correct most astigmatism. The RGP lenses can be less comfortable to wear than soft lenses. In some cases the RGP lenses can have an adjustment period of a few days to break in.
Hybrid RGP lenses have an RGP core with a soft material formed on the outside surface of the RGP core. The soft material can improve the comfort level of the hybrid lens while still offering some of the benefits of the RGP lenses.
An additional challenge with contact lens technology is the tendency for protein binding and absorption at the ocular site. For example, a contact lens may bind proteins on the lens to create protein deposits in the eye area. Additionally, the lens can cause structural changes including protein denaturation that can elicit an immune response such as tearing, reddening, or swelling in the ocular region. Accordingly, contemplated embodiments provide for contact lenses and methods of making lenses with improved resistance to undesirable protein interactions at the ocular site.
A further concern with contact lens use is that some users experience discomfort that is similar to the profile of patients that have a dry eye disease. Dry eye disease is considered to be a consequence of a disruption of the tear film that covers the surface of the eye, or a particular vulnerability to such disruption. This tear film is an aqueous layer disposed between an underlying mucous layer that is secreted by corneal cells, and an overlying lipid layer that is secreted by Meibomian glands on the conjunctival surface of the eyelids. The tear film includes an aqueous pool that transits across the eye surface, having a flow path that, to some degree, may be independent of the lipid layers that it is disposed between at any point in time.
Integrity of the tear film is important for such critical functions as oxygen and ion transport, and lubricating the eye surface, which is subject to a constant sliding contact by the eyelids. It is likely that dry eye disease actually exists as a spectrum of tear film vulnerability to disruption. In some cases, patients may have a low-level dry eye disease that manifests when the integrity of the film is challenged by the presence of a contact lens. To address this concern, some embodiments of the invention provide for contact lens technology that diminishes or substantially eliminates contact lens disruption of the tear film.
As can be appreciated, dry eye disease may be referred to herein as a non-limiting example for illustration purposes. The methods and devices described may be used to treat or prevent other ocular pathologies including, but not limited to, glaucoma, corneal ulcers, scleritis, keratitis, iritis, and corneal neovascularization.